DISCLAIMER: Vacuum tube circuits work with dangerously high voltages. Do not attempt to build circuits presented on this site if you do not have the required experience and skills to work with such voltages. I assume no responsibility whatsoever for any damage caused by the usage of my circuits.

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Sunday, August 7, 2016

The Future of ELROG Tubes


It has been a bit quiet about Elrog during the recent months and I would like to give an update about the state of the company and the future. I have some bad and some good news. The bad news is that due to various reasons Elrog struggled financially and was forced to enter the insolvency process. The good news is that Elrog tubes will continue to be produced. I founded a new company which acquired all assets and machines of Elrog. This company will continue the manufacturing and distribution of Elrog branded tubes.

The name of the company is Deutsche Elektronenröhren Manufaktur GmbH. This translates to German Electron Tube Manufactory Ltd. The name of the company was chosen to represent the heritage and tradition of Elrog GmbH & Co Elektronenröhren KG. The bright yellow glow of thoriated tungsten filaments was selected as the company colour.

I am very happy to announce that two key people committed to come on board of the new company. Without those it would be impossible to continue the production. Matthias Klepper who was managing production and development at Elrog, will be the Chief Technology Officer of the new company. He will continue to overlook production and new tube development. I got to know Matthias very well during the recent months. He brings a vast knowledge and experience in different fields. He especially impressed me with his deep understanding of vacuum tube technology and production as well as his electronics expertise especially in audio amplification. Vacuum tubes require know how in electronics, physics and chemistry all of which Matthias masters in an impressive way. In addition to that I also found a close friend in him who shares my passion for music and audio technology. 

And I am very happy that Dr. Schaffernicht, the founder of Elrog, also committed to be part of the new operation in an advisory role. He brings in his vast experience in tube manufacturing which spans all the way back to the Telefunken era. The Elrog tubes are his life achievement which we will continue to carry into the future. This is both a great honour and a great responsibility.

300B, 211 and 845 tubes will be continued to be produced at the same premises in the city of Hagenow on the same equipment. During last week the production line has been refurbished. Production will be resumed in the coming week. The tubes will continue to carry the ELROG name.

Originally I planned to announce this news at the end of this month. But since I keep getting inquiries I decided to share this earlier. Especially since the elrog.com website is currently down and the Elrog email address is not reachable in the moment. It will take some days or even more than a week until the website is released and transferred to the new company. Until then please contact me under the VinylSavor address which can be found in the link Impressum / Contact on the upper left of this site. There is also a phone number. Please use this contact information for any inquiries or questions until the elrog.com site is accessible again.

Any emails sent to info (at) elrog (dot) com during the last week have not been read. Also access to the emails had been intermittent before that time. In case you sent a message to that address and did not get a reply, please contact me and I will follow up.

Please note that Deutsche Elektronenröhren Manufaktur GmbH is not the legal successor of Elrog GmbH & Co Elektronenröhren KG. We cannot assume any liabilities of the old company. Nevertheless we will do our best to resolve any open issues or warranty claims in an amicable way.

In case you are sending inquiries please allow for some time to respond since there is a lot of work in the beginning. All emails will be answered. We are also starting to take preorders. New tubes will be available in September. Some limited stock of tubes is already available now for serving urgent needs. It is expected that demand might be higher than production capacity throughout the rest of the year. One of the top priorities will be to resume production at the highest possible quality level rather than maximum output.

Inquiries from distributors and resellers are welcome. Please contact me if you are interested to represent The Elrog brand in your area and we will discuss details.

These are exciting times and I am hoping for your support to re-launch the brand and continue vacuum tube manufacturing in Germany. I would like to thank all the loyal customers of Elrog and would be happy to continue to serve you with german made vacuum tubes.

Best regards


Tuesday, August 2, 2016

The Ultimate Phono Stage - Part 2


Assembly of the all silver, fully balanced EC8020 LCR phono stage is complete.

The only part missing is the wooden frame, face plate and back plate with the connections. These will be added after initial testing.

Dark maroon red metallic transformer covers complement the gold coloured top plate nicely.

The array of 8 EC8020 triodes is always an impressive sight.

The power supply is finished as well:

The transformer cover will be added at the end after testing and fine adjustment of voltages.

Part 3 with the completed phono stage and some initial sound impressions will have to wait a bit due to some travelling. Please be patient and stay tuned.

Best regards


Tuesday, July 26, 2016

D3a Differential Phono Preamplifier, Part 3


In this last post about the fully differential phonostage with D3a tubes, I am sharing some more photos, also with the unit glowing in the dark and some assessment of it's sound.

Here a photo of the phono with the power supply:

As mentioned it shares pretty much the same circuit and parts quality with the differential EC8020 phono.

The D3a tubes glowing away:

8 D3a tubes playing in unison.

So the big question: How does it sound?

This unit shares the same strengths with the EC8020 version. The absence of capacitors in the gain stages shows it's advantage by removing the last bit of grain from the sound and giving extremely revealing timbre and details.

The result is surprisingly close to the EC8020 version. So the sound descriptions given for that one are mostly valid.

The EC8020 gives a tad more resolution, ambience and decay of tones. It is for those who only accept the best of the best.

The D3a however is a close runner up at significantly less tube costs. Let's see how the ultimate version with all silver transformers and plate chokes will do. Stay tuned!

Best regards


Wednesday, July 20, 2016

Tube of the Month : The 80


Let's have a look at a rectifier tube this month, the 80.

The 80 is a 'classic' full wave rectifier tube. It is directly heated.

Thus it only needs 4 pins, 2 plates and the 2 filament connections. Which fits on a UX4 base. The pinout is shown on the left. As all the classic rectifiers it has a 5V filament which consumes 2A. It is a rather small rectifier which cannot deliver a lot of current. 135mA max when a choke inout filter is used. Less with a capacitor input filter. For all details regarding the technical specs refer to the data sheet. This rather modest current capability makes it only usable for preamplifiers or small power amps which do not draw a lot of current. A stereo 45 amplifier is about the maximum which comes to mind and that is also what I have used this tube for many years ago before I turned to TV dampers. It could also supply a mono 2A3 single ended amp.
Being a classic full wave rectifier it requires a power transformer with a center tapped high voltage winding unless it is augmented with two single diodes to create a bridge rectifier. My samples of this tube had been lying in storage since well over 10 years since the amp I used them in has been dismantled a long time ago. I pulled them out of the drawer to shoot some photos for this post. The 80 has been produced over a very long time. It started it's life in the 1920ies in globe shape as UX280. It adopted the ST shape in the 1930ies and was even packaged in the much slimmer GT tubular bulbs at the end of it's life. It was made by all the major tube manufacturers. Let's start with the gorgeous UX280 made by RCA:

View from another angle:

Close up to the interior:

Here the two plates and the glass stem which aligns the electrode is nicely visible:

View from the top:

Close up to the ribbon filament:

Side view:

The top with the RCA logo:

A Cunningham CX380 also made by RCA:

Detail close up:

More views:

From the top:

Glass stem:

Philco made by Sylvania:

From the side:

Close up showing the ribbon filament:

The plates:



The top:

This one has the plates quite close to each other:


The top:

Another RCA this time with GT straight sided bulb:

Detail close up:

Another view:

The plates look similar to those in the ST shaped RCA shown above:

The GT version is rather small compared to a ST tube:


The tube with the box:


A JAN-80 made by Sylvania for the military in sealed box:

The box also carries the VT number which in this case is 80 as well (which is not the case for all tubes and can cause confusion).

Apparently this tube was inspected in 58. Which is indicated by the stamp and sticker:

The boy was made such that the tube could be tested without breaking the sealed packaging:

The top flap could be opened.

So the tube could be pushed down a little to expose the pins for testing:


National Union 80:

The plates:

A 80 with the filament lit up:

Close up:

The mica disc obstructs much of the view to the filaments:

Since the globe tubes don't have mica discs they give a much better view to the glow:

I hope you enjoyed this rectifier presentation.

Best regards